In general, the purpose of a preoperative evaluation is to determine if you are healthy enough to undergo an operation. As I mentioned, surgery is really nothing more that a controlled injury, and your body responds to surgery just as it would to any other stress. You will find that you may feel very frightened or anxious both before and after surgery. This is your body’s fight or flight response in action. After surgery, you will also find that you retain fluids, and your weight may increase several pounds rapidly. This is simply another manifestation of your body’s response to stress and will resolve as your recovery progresses.
Other organs are involved in the stress response as well, and it is for this reason that much of the testing is done. It is important to know that the function of your heart, lungs, liver, and kidneys are adequate. If not, you may need to have some medical “tuning up” prior to your surgery. It is not uncommon for someone who goes in to see the doctor for foot pain to wind up being treated for diabetes or even having an open-heart operation. If you have been good about seeing your doctor regularly, things like this probably won’t happen to you, but there are many people who only see their physicians after problems become unbearable. These people often find that they are harboring more than the problem that brought them in to see their doctor.
You should expect to have your blood drawn on more than one occasion while preparing for surgery. It is likely that your primary care physician has drawn blood from you to determine what is causing the problem that brought you into the office. Once you are referred to a surgeon, you will probably have more blood drawn for tests that are more specific to the problem diagnosed. Beyond those tests, you will be given a battery of tests that assess the function of your vital organs. Blood will be drawn to determine the number of oxygen-carrying red blood cells (RBCs) that you have. This same test can also determine the number of infection-fighting white blood cells (WBCs) you have, as well as the number of clot-forming cells called platelets. You will probably hear your doctor talk about your hemoglobin (the amount of iron in your red blood cells), your hematocrit (the volume of RBCs in your blood), and your white count (the number of WBCs in your blood). Unusual values in these numbers may require a postponement of your surgery until it can be determined why you have abnormal results. In most otherwise healthy people, this test comes back normal. The next test is called a coagulation profile, sometimes referred to as a PT and PTT. This test is designed to determine if your blood clots in the normal fashion. As you can imagine, performing surgery on a patient whose blood does not clot normally can be quite a challenge. Medications can be administered to temporarily correct abnormal blood clotting; however, if you are scheduled for elective surgery and you have a disorder of coagulation, your surgeon will want to know where the problem lies and will try to correct the problem prior to your operation. At a minimum, you will also have blood drawn to determine your kidney (also called renal) function. These two tests measure the amount of protein breakdown products circulating in your blood, namely blood urea nitrogen (BUN) and creatinine; again, it is important to have normal kidney function prior to surgery. If your test shows abnormalities in this regard, you will probably be asked to see a nephrologist (kidney doctor) prior to surgery. Other common tests prior to surgery include a glucose level to determine if you have diabetes, and one to measure electrolyte levels.
Most of this testing will be done prior to your arrival at the hospital, so that the results are available before you enter the operating room. If you are having minor surgery, such as the removal of a growth from your skin, these tests may not be performed. When you arrive at the hospital, expect to have more blood drawn. This is sometimes done in conjunction with the placement of an intravenous (IV) catheter, but sometimes you will require more than one “stick” or needle insertion to accomplish this. The blood drawn on your admission is typically used to perform a type and crossmatch in the event that you require a blood transfusion. These tests can not be done earlier because the blood samples used for this are good only for a few days. If you have had any abnormal lab values on your initial blood testing, repeat levels may also be drawn prior to surgery.
Along with the blood drawn at your preoperative visit, most physicians will ask that you submit a urine sample as well. Urine samples are useful for testing a number of things, as many of your body’s metabolites are removed in the urine. A urinalysis (or UA) can indicate your state of nutrition, your level of hydration (or dehydration), the presence of diabetes, or the presence of an infection. If your UA shows that you have a urinary tract infection (that is, an abnormal number of bacteria in your urine), your doctor will prescribe antibiotics prior to surgery. This is because wound infections are much more common in patients who have an underlying infection at the time of surgery. For those going to the hospital to have a fistula or graft placed for dialysis access or a kidney transplant, you will have already had many more extensive tests performed to determine the function of your kidneys.
The preoperative chest x-ray (CXR) is not done on all patients, but it is fairly routine for those patients over the age of 50 or patients who have a history of smoking or lung disease. If you fall into one of these three categories and you have not had a CXR in more than three months, you will probably need to have one prior to surgery. In obtaining this test, your surgeon is looking for a number of things, including the presence of an infection, the indication of lung disease, or the presence of a lung mass. Additionally, chest x-rays let physicians look at the size of your heart and whether any fluid is accumulating in your lungs (a condition known as congestive heart failure). Abnormalities on the chest x-ray may mandate a trip to a pulmonologist (lung specialist) or cardiologist (heart specialist) prior to elective surgery.
Smokers or patients with known lung disease will need additional testing prior to surgery. If your CXR is abnormal or if you are going to have a lung resection, your surgeon may want you to have pulmonary function tests (PFTs). This series of tests determines how well you move fresh air in and out of your lungs. It also allows your surgeon to tell how well you absorb the oxygen that you inspire. Patients who have a mass in their lung will need a chest CT (or cat scan), which provides very high resolution images that will aid your surgeon in determining which procedure to perform. In some parts of the country, an MRI will also be performed in the preoperative period. Finally, your doctor may order an arterial blood gas (ABG) prior to surgery. This test requires that a needle be inserted into one of your arteries (usually in your wrist or groin), and determines the amount of oxygen and carbon dioxide in your blood, it also determines the pH. (or acidity) of your blood. This information is important in determining whether you are able to withstand an operation, and is also necessary for your postoperative care.
Electrocardiograms (EKG, also known as an ECG)
Obtaining an EKG prior to surgery is an important part of the preoperative work-up. As mentioned before, surgery causes tremendous stress on the body, and one of the organs most important in the stress response is the heart. Just remember back to the last time you were frightened or upset, and think about the pounding feeling you had in your chest. This is the effect that the stress hormone epinephrine (adrenaline) has on your heart. In response to stress, your heart not only beats faster, but it also beats more forcefully. If you have a normal heart, this is no problem, but if your heart has a poor blood supply (as you see in patients with coronary artery disease), this added work can cause serious problems. The EKG is not a forward-looking test, in that it can not predict what will happen to your heart in the future. People with normal EKGs have heart attacks every day. What the EKG can do is look at the electrical activity generated by your heart. The pattern of the heart’s electrical activity can tell your doctor if you have ever had a heart attack in the past (which you may not even have known about). It also shows if your heart is in a normal rhythm, how well the conduction system of the heart works, and if any of the chambers of the heart are working too hard (a condition call hypertrophy).
An abnormal EKG will usually trigger a series of other tests, including echocardiography and stress testing. In severe cases, you may be asked to have a cardiac catheterization immediately. An echocardiogram is a noninvasive (i.e., non-painful, requiring no needles) test which uses sonar waves (similar to those on submarines) to create an image of the heart. Using this test, a well-trained cardiologist can determine the heart’s size, the function of its valves, any abnormal thickening of its walls, and the pressures inside the chambers of your heart. A stress test does what its name implies, it puts your heart under stress either by exercise or by injection of drugs, which in turn alters the heart’s perfusion (blood supply). The heart’s response to this stress is then measured by EKG or by radioisotope scanning. This will let your doctor know if any area of your heart has a poor blood supply, and if you are at risk of having a heart attack during, or immediately after, your surgery. Please note again that a normal stress test or echocardiogram does not rule out the possibility of a heart attack, but normal results suggest that your heart is in good enough condition that a heart attack is unlikely.
For those of you who have abnormal results on the preceding tests, or those of you who are being considered for coronary artery bypass graft (CABG) surgery, the next step is a cardiac catheterization. This is an invasive test in which a cardiologist will pass a long, thin tube through one of your arteries (usually in your groin or upper arm) into the blood vessels that supply your heart. A contrast material, which shows up on x-ray, will then be injected into those arteries, and the results of these injections will be captured on film. By reviewing this film, a cardiologist or cardiac surgeon can tell whether you have narrowing or blockages in any of the arteries supplying your heart. If a problem is found, you may need to have an angioplasty (dilation of the narrowed artery, usually with a balloon) or bypass.
Prior Medical Conditions
It should come as no surprise that as people get older, they develop more medical problems. As surgical techniques have evolved, surgeons have gained the ability to operate on patients who only a few years ago would have been considered “too sick” for an operation. In order for this to occur, it is becoming more and more important for surgeons to optimize the medical treatment of the non-surgical diseases that patients have. For this reason, your surgeon may refer you to one or more medical specialists prior to your surgery. Your heart, lungs, kidneys, immune system, liver, and endocrine system all must be in the best shape possible prior to surgery. If every organ is working as well as it possibly can, this will minimize the chance that something will go wrong once you are subjected to the stress of surgery. Evidence of prior medical conditions will show up on the preoperative testing your surgeon performs; however, it is ultimately your responsibility to keep your surgeon informed of your past problems and treatments. After all, it is your health we are working to restore.
Unless you are scheduled for a minor surgical procedure not requiring anesthesia or sedation, you will be under the care of more than one physician while in surgery. Anesthesiologists or nurse anesthetists, their partners in anesthesia care, play an essential role in the success of your operation. Many advances in surgical technique have followed advances in anesthesia care; as such, the anesthesia you receive is as important as the procedure you undergo. Prior to surgery, a professional from your anesthesiologist’s department will assess your medical condition and anesthetic risk. The questions they ask will be largely identical to the ones asked by your surgeon (and probably your primary care physician as well). It is easy to become frustrated when asked the same questions over and over again, but rest assured that the redundancy built into the system is for your own benefit. If you can, fill out the PreOp-Worksheet before you go in for preoperative testing or anesthesia evaluation. I assure you it will save you both time and effort.
The PreOp-Worksheet, which is included in this guide, will give you the opportunity to provide your physician with all of the information he or she will require to give you the best care possible. You should look at the worksheet soon to get an idea of the types of questions it asks. Most of the questions are self-explanatory, and Chapter 10 of this guide will help you complete the complicated ones. It will require a small investment of time and effort in order to complete the worksheet, but I guarantee that it will be time well spent. The questions in the worksheet are the ones I struggle to answer on a daily basis while caring for surgical patients. Yet the information required to fill in the questionnaire is all at your fingertips while you are sitting in your home. Reading this guide will hopefully provide you with the answers you are looking for regarding your surgery. Completing the worksheet will increase the likelihood that your health care providers have the information they need to best help you.